There is known an apparatus for electrochemical machining of metal parts, (cf. Inventor's Certificate No. 462,690 CL B23P 1/04 granted in the USSR)
The known apparatus comprises an electrode-tool, mounted on a component part of the apparatus mobile in the direction of the working feed, and a contact system formed with a pair of detachable contacts for connection to a process current circuit. One of said contacts is mounted on the mobile component part, and the other, on a stationary component part of the apparatus.
The ratio of the lengths of the mating sections of both contacts is such as to allow closing the process current circuit throughout the range of heights of parts being machined and to open the circuit when the electrode-tool is backed away.
Reliable both making and breaking of the process current circuit of the apparatus are obtained by accurate manufacture of the contacts coupled to their large size and adequate stiffness.
This results in an excessive consumption of metal and higher costs while providing no guarantee of accurate mating of contacts whose shafts may shift one with respect to another due to vibrations in service. The contact systems suffer from a rapid wear and burning of contacts, these disadvantages affecting adversely the service reliability of the apparatus as a whole.
In addition, the beginning of the electrochemical machining fails to agree with the required optimum spacing of the electrode-tool and of a part being machined so that the resultant machined configuration is blurred, and the accuracy of machining, impaired.